请优化以下代码
public static void main(String[] args) throws IOException {
File file = new File("some file path");
List list1 = new ArrayList();
FileInputStream fileInputStream = new FileInputStream(file);
byte[] bytes = new byte[1024];
int i = fileInputStream.read(bytes);
if(i > 0) {
do {
i = fileInputStream.read(bytes);
String s = new String(bytes, 0 , i);
list1.add(s);
} while(i != -1);
}
i = fileInputStream.read(bytes);
String start = new String(bytes, 0, i);
list1.add(start);
for (int i1 = 0; i1 < list1.size(); i1++) {
String s = (String) list1.get(i1);
if(s.contains("1")) {
s = s.replace("1", "a");
} else if(s.contains("2")) {
s = s.replace("2", "b");
} else if(s.contains("3")) {
s = s.replace("3", "c");
} else if(s.contains("4")) {
s = s.replace("4", "d");
}
list1.remove(i1);
list1.add(i1, s);
}
FileOutputStream fos = new FileOutputStream(file);
for (Object o : list1) {
fos.write(o.toString().getBytes());
}
}
